1. Field of the Invention
The present invention relates to a photovoltaic photo-receptor and an electrophotographing apparatus. More specifically, the present invention relates to a novel photovoltaic photo-receptor and an electrophotographing apparatus using the same, in which an electrostatic latent image corresponding to a light image which is irradiated onto a photovoltaic photoreceptor is formed on a surface by means of a photovoltaic function of a semiconductor photovoltaic layer.
2. Description of the Prior Art
An electrophotographing apparatus which utilizes a corona discharge as shown in FIG. 1 is generally wellknown. With reference to FIG. 1, in this conventional electrophotographing apparatus, around a photo-receptor 1, a charger 2, a light source 3, a developer 4, a transcriber 6, an eraser lamp 8, a cleaner 9 and etc. are arranged for respectively performing the process such as corona charging, era and etc.
A surface of the photo-receptor 1 being rotated is uniformly charged by the charger 2 and, when a light image is irradiated by the light source 3, an electrostatic latent image is formed on the surface of the photo-receptor 1 in accordance with a photoconductive function. The electrostatic latent image is toner-developed by the developer 4 and a toner image is transcribed onto a paper 5 by the transcriber 6. A transcribed toner image is fixed on the paper 5 by a fixing device 7 and the paper is discharged. The residual static electricity on the surface of the photoreceptor 1 is erased by the eraser lamp 8 and a residual toner on the surface of the photo-receptor 1 is removed by the cleaner 9.
In the electrophotographing apparatus which utilizes the corona discharge as shown in FIG. 1, the charger 2, light source 3, developer 4, transcriber 6, eraser lamp 8, cleaner 9 and etc. must be arranged around the photo-receptor 1, and therefore, there was a disadvantage that the structure thereof becomes complex.
In view of such a problem, recently, an electrophotographing apparatus which does not utilize the corona discharge as shown in FIG. 2 was proposed. With reference to FIG. 2, in this newly proposed electrophotographing apparatus, a developing device 11 is arranged above an outer surface of a photo-receptor 10, a transcribing roller 15 is arranged below the outer surface, and an LED array head 13 is arranged inside the photo-receptor 10. In more detail, the photo-receptor 10 includes a cylindrical transparent substrate 10a made of a glass, and a transparent electrode 10b and a photoconductive layer 10c are sequentially laminated on an outer surface thereof, and a developing bias 12 is applied between the transparent electrode 10b and a magnetic roller 11a constituting the developing device 11. An electric conductive toner is adhered onto an outer surface of a sleeve 11b which covers an outer surface of the magnetic roller 11b, whereby a magnetic brush is formed and a tip end of the magnetic brush is brought into contact with an outer surface of the photoconductive layer 10c.
A charge is injected from the developing bias 12 to the photoconductive layer 10c through the electric conductive toner so that the photoconductive layer 10c is charged approximately the same potential as the developing bias 12. On the other hand, a light image projected by the LED array head 13 is irradiated into the photoconductive layer 10c from an inside of the cylindrical transparent substrate 10a. Therefore, an electrostatic latent image is formed on the photoconductive layer 10c in accordance with a photoconductive function thereof, and the electric conductive toner of the magnetic brush is adhered onto the electrostatic latent image so that a toner image is formed on the surface of the photoconductive layer 10c. The toner image is transcribed onto a paper 14 by the transcribing roller 15.
A residual toner on the surface of the photo-receptor 10 is removed by a sweeping force of the developing device 11 and a magnetic force of the magnetic roller 11a. Therefore, the charging, exposing, developing and cleaning with respect to the photo-receptor 10 are performed at approximately the same time by the developing device 11 and the LED array head 13, and therefore, the structure and the process can be drastically simplified in comparison with a conventional electrophotographing apparatus as shown in FIG. 1.
In the newly proposed electrophotographing apparatus as shown in FIG. 2, as described above, the structure and the electrophotographing process can be largely simplified, while it is difficult to stably obtain a good image quality because the charging is performed by utilizing the developing bias which is applied in developing. More specifically, the developing bias should be set at the most proper value by taking both of a charging characteristic of the toner and a potential of the electrostatic latent image into consideration, but in a case where the developing bias also performs the charging of the photo-receptor 10 as done in FIG. 2 conventional example, a voltage value which is originally necessary for the developing bias and a voltage value which is necessary for charging are necessarily not coincident with each other, and therefore, it is difficult to set a voltage value of the developing bias 12 by which the both can be satisfied at the same time.